This invention relates to a mechanical assembly that regulates the temperature of an integrated circuit chip (IC-chip) by pressing a temperature controlled heat-exchanger against a planar surface of the IC-chip.
One particular use for the above mechanical assembly is in a chip testing system. There, test signals are sent to the IC-chip while the mechanical assembly maintains the temperature of the IC-chip at a set point.
In the prior art, one mechanical assembly which regulates the temperature of an IC-chip is shown in FIGS. 1 and 2 of U.S. Pat. No. 4,791,983. The mechanical assembly in patent '983 includes a coil spring 20 which presses a planar surface of a liquid cooling jacket 15 against a planar surface of the IC-chip 11. Squeezing those two planar surfaces together enables heat to flow by thermal conduction from the IC-chip 11 to the liquid cooling jacket 15.
But due to various manufacturing tolerances, the planar surface of the IC-chip in a chip testing system can be oriented at different angles relative to a nominal position. To accommodate these different angles, the mechanical assembly in patent '983 includes a guidepost 18 which has one end that is rigidly attached to the cooling jacket 15, and has an opposite end that pivots on a frame 14. The coil spring 20 is coiled around the guidepost 18. Thus the guidepost 18, together with the coil spring 20 and the cooling jacket 15, can tilt at different angles.
After initial contact occurs in patent '983 between the planar surface of the cooling jacket 15 and one edge of the IC-chip 11, the guidepost 18 must pivot on the frame 14 to make the cooling jacket 15 lie flat against the IC-chip 11. However, the present inventors have determined that as the guidepost 18 pivots on the frame 14, the spring 20 can exert a lateral force on the cooling jacket 15 which may cause a gap to occur between the IC-chip 10 and the planar surface of the cooling jacket. When this gap occurs, the IC-chip 10 will not be adequately cooled. This lateral force problem is analyzed herein in detail in conjunction with the Detailed Description of FIGS. 4 and 7.
Also in the prior art, another mechanical assembly which regulates the temperature of an IC-chip is shown in FIGS. 10 and 11 of U.S. Pat. No. 6,116,331. This mechanical assembly includes a single leaf spring 80 which presses a planar surface 91 of a heat-exchanger 90 against a planar surface of an IC-chip.
However, the leaf spring 80 in patent '331 lies parallel to the planar surface 91 of the heat-exchanger 90, and that leaf spring must have a certain length in order to have the proper flexibility. If the leaf spring 80 is too short, it will be so stiff that the heat-exchanger 91 will press against the IC-chip with too much force and thereby damage the IC-chip.
But as the length of the leaf spring 80 is increased, the density with which multiple copies of the mechanical assembly can be arranged side-by-side in a chip testing system is decreased. Thus, the total number of IC-chips which can be tested concurrently per unit area in a chip testing system is decreased.
According, a primary object of the present invention is to provide an improved mechanical assembly for regulating the temperature of an IC-chip in which all of the above drawbacks with the prior art are overcome.